Festival spokesperson Megan Bulla says they still have 3,000 entries left for the half marathon, which is capped at 35,000 participants.

The Mini has sold out the last 12 years, but the sell-out date keeps getting later. One year it sold out in late November, last year it was April 1.

Bulla said she didn't think "there was any one reason" it hadn't sold out this year, but noted the increased competition from other races and events.

She also noted the especially harsh winter making it more difficult for people to get outside and train.

Bulla said one big change this year is the addition of "wave starts," to alleviate the congestion when all runners go off at the start.

Instead, they will be grouped in waves which will be start 12-15 minutes apart. She said the change will add an hour to the race time, but should ease the crowing, especially in the first few miles of the race.